


plausible deniability

by coronaofastar



Category: The Last Hours Series - Cassandra Clare, The Shadowhunter Chronicles - Cassandra Clare
Genre: Alternate Universe - Modern Setting, Alternate Universe - No Powers, Established Relationship, Fluff, Humor, M/M
Language: English
Status: Completed
Published: 2020-11-10
Updated: 2020-11-10
Packaged: 2021-03-09 04:01:11
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,609
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27488503
Author URL: https://archiveofourown.org/users/coronaofastar/pseuds/coronaofastar
Summary: “Which Thomas,” Alastair said vaguely.It took her a second to understand what he was asking—and another to process it, for all the sense it made. “Your Thomas, Alastair.”Alastair opened his eyes. He looked very bewildered. “I have a Thomas?”It was possible (Cordelia thought, glancing up at Alastair’s IV stand) that her brother wasn’t all that there at the moment.Ever been so high on the good hospital meds that you forgot you were engaged?
Relationships: Alastair Carstairs & Cordelia Carstairs, Alastair Carstairs/Thomas Lightwood
Comments: 44
Kudos: 184





	plausible deniability

**Author's Note:**

> on GOD this is not what I meant when I said I was writing more thomastair. this entire thing was unplanned, except for the part where I planned to finish this last week as a treat when a lot of people were stressed, and well, it's not last week anymore. also not me removing like 300 words in order to get this tied up. you gotta cut your losses sometimes
> 
> I believe the inspiration for this trope is from [this video](https://www.youtube.com/watch?v=EcLYd6SjtA0). which trope? you'll see.
> 
> cw: surgery, hospitals. surgery is referenced and the hospital is just the setting (with IVs mentioned like. twice?), but do take care of yourselves, click away if needed, and let me know if I should tag anything else!

Alastair woke up in the five minutes Cordelia had insisted were _fine, Thomas, go get coffee, he’s not going to wake up while you’re gone,_ and when Thomas came back he was probably going to look betrayed. At the moment, though, she was more preoccupied with her brother.

“Alastair _joon,_ ” she said softly, putting down her paper cup of tea to take Alastair’s right hand before he could tug on the IV catheter. Alastair scrubbed at his face with his left and blinked groggily at her. “There you are, hi. How are you feeling?”

It took him a solid minute to answer, blinking slowly at his surroundings. Still waking up from the anesthesia. “Bit sore,” he said, voice thick with sleep. “Tired. Mhmm I had surgery?”

“Laparoscopic surgery, to remove your appendix.”

“Hm,” Alastair murmured, and closed his eyes. Cordelia rubbed her thumb over his knuckles and added, “I’m surprised you remember being told that at all—Thomas says you were well drugged up.”

Alastair’s brow creased, though he still had his eyes closed. “Thomas.”

It wasn’t quite a question, but she took it for one anyway. “He’s due back in a bit. Just gone to get coffee.”

“Which Thomas,” Alastair said vaguely.

It took her a second to understand what he was asking—and another to process it, for all the sense it made. “Your Thomas, Alastair.”

Alastair opened his eyes. He looked very bewildered. “I have a Thomas?” 

It was possible (Cordelia thought, glancing up at Alastair’s IV stand) that her brother wasn’t all that there at the moment.

“Hey.” That was the Thomas in question easing back into the room, voice hushed, carefully bearing a carrier tray with two paper cups and a plastic spoon sticking out of one. He looked rather peaked, although that was to be expected—he’d been up with Alastair all night and _hadn’t_ gotten any medically-induced shut-eye. He was so preoccupied with trying to close the door as soundlessly as possible that he hadn’t looked toward the bed. “Sorry I took a while. Nurse caught me in the hall. Has he—”

He stopped. He put his hand to his mouth for a moment and Cordelia thought for a split second that Thomas might cry—but then he took it away and just _smiled._ She read exhaustion there; affection, too, and above all, relief. “Hi, love,” he said, so, so softly.

Alastair blinked at Thomas, looking stunned. “‘Lo,” he said. “You’re very tall.”

Cordelia stifled her giggle, but Thomas burst into soft, amused laughter. “I am,” he said patiently, setting the carrier tray on the bedside table. He drew up a chair as close to Alastair’s hospital bed as he could and reached over for his cup of terrible hospital coffee.

“He’s a little out of it,” Cordelia explained.

“No, I’m not,” Alastair said, almost immediately. Then: “...out of where?”

“Wouldn’t worry about it,” Thomas said, plucking up the other paper cup with the spoon in it. He nudged it into Alastair’s hand. “Ice chips, darling. You’ve got to be thirsty.”

Alastair took the ice chips. Cordelia let go of her brother so he could have both hands to work with, but he didn’t start in on them, just sort of...stared at Thomas with an open soft expression, a bit helpless in its adoration. _Have you ever seen someone so beautiful,_ said the expression. _Have you ever loved someone so much._

Thomas noticed. He smiled, though there was a worried little crease between his brows. “You alright?”

“We should get married,” said Alastair, very seriously.

Cordelia pressed her fingers to her mouth in an effort to not start giggling madly. She fumbled for her phone and set it recording just as Thomas grinned at him. “Should we, now?”

“Yes,” Alastair said, with all the air of someone pointing out the obvious. “You’re really very tall.”

“This is a strange moment to be learning why you’re really marrying me,” Thomas said fondly.

Alastair blinked. “Pardon, sorry?”

“Alastair,” Cordelia said, trying valiantly not to laugh; Alastair turned towards her, bemused. “Oh, goodness—Alastair, who do you think this is?”

She made sure to point the camera at Thomas, who was trying to hide how funny he found this behind his coffee cup. Alastair frowned. “...Thomas,” he said, after a very long pause, and looked almost helplessly at him. “I think.”

“Right, but do you know who he is? To you?” Cordelia clarified, after Alastair just blinked at her in confusion.

“...should I?”

It was the funniest thing he could have said in that moment, and Cordelia was just barely able to quash her amusement. Thomas was not quite so skilled. She could see him behind Alastair, fist pressed to his mouth, shoulders shaking with silent laughter. “Well, if you’ve just proposed marriage.”

“I don’t—” Alastair pulled a face, a little like their younger brother Reza when he was being made to eat his vegetables. “Can’t I just like a man?”

“I mean,” Thomas put in, in a voice of barely suppressed laughter, “no complaints?” He took Alastair’s hand, laced their fingers together. Alastair looked surprised but rather pleased all the same.

“What do you like about him?” Cordelia asked innocently, and Alastair blinked at her like he’d forgotten she was there.

“Hm. Well.” He seemed to be giving it a great deal of thought. “He’s very tall.”

“It’s so I can reach the marmalade when it ends up on the top shelf, isn’t it,” Thomas said dryly.

“He’s beautiful,” Alastair continued, and smiled at him a bit helplessly. There was the soft expression again. Regular Alastair was not quite as soppy, at least not openly, and Cordelia had a moment of hilarity imagining her brother’s horrified expression if he could have seen himself, though Thomas was looking at him with all the fondness in the world. “Very striking. He, um. He has a face—”

“I do have a face,” Thomas agreed.

“—and he brought me ice chips!” Alastair added brightly, gesturing limply with the cup. It tilted dangerously and Thomas said, “Alright—” and swooped in to rescue it.

“Sorry, revision,” Alastair said, watching the cup be taken away. “He’s taken my ice chips. I still like him, though.”

Cordelia bit her lip. “Right, then,” she said, once she’d beaten back her latest fit of giggles. “Strong arguments from the moving party. Ah, Tom?” She caught Thomas’s eye. “Would you like to make your statement?”

Thomas smiled. “Right,” he said, and let go of Alastair’s hand. Alastair looked put out and then badly pretended he was not.

“It’s alright you don’t remember me,” said Thomas. He was gently working off a ring from his right hand, a platinum band set with a slant of sapphires that hadn’t been sized for him and therefore only fit on the index finger. “But we’re very close, actually. Close enough that you entrusted me with this before they took you for surgery.”

“Are we flatmates?” Alastair said blankly, which made Thomas laugh and Cordelia snort.

“In a sense.” Thomas held out the ring, but when Alastair made to take it, he took Alastair’s hand and slid the ring into place on the fourth finger.

Alastair looked perplexed.

“Funny you should propose marriage,” said Thomas.

There was a beat of perfect comedic silence. Alastair stared down at the ring that he—at the moment—likely didn’t recall having ever possessed or even _seen_ in his life. “Oh,” he whispered, and then, more fervently, “Oh, _shit.”_

That did them in, her and Thomas. Cordelia burst out laughing and so did he, and all the while Alastair looked like he’d been introduced to the sun for the first time. “We’re married?”

Thomas managed to pull himself together, though a helpless laugh or two still slipped through. “Engaged, love,” he corrected gently.

Alastair was wide-eyed. “How long?”

“Five months. Well, nearly.” Thomas thought for a moment. “Five months this Saturday.”

Alastair said, _“Whoaaa,”_ under his breath, so quietly Cordelia nearly didn’t catch it and prayed that the video did. He stared at the ring for a bit, twisting it thoughtfully, and then looked up abruptly as though something had just occurred to him. “Are you in love with me?”

Thomas laughed so hard he doubled over, resting his forearms on his legs. “No,” he wheezed. “Clearly I’m marrying you for taxation purposes.”

“You _are_ in love with me!” said Alastair, sounding inordinately pleased about this. He reached for Thomas’s hand, and Thomas took it.

“‘Course I am,” Thomas murmured. They made a lovely tableau like this, angled toward each other, worn out and fond all at once. 

“Perhaps we should stop teasing you, hm?” Thomas said eventually. Cordelia quietly ended the video and slipped her phone back into her purse as he leaned forward to kiss Alastair on the forehead, brushed a strand of black hair off his temple, and smiled. “You’re going to be quite embarrassed about this when you’re in your right mind again.”

“No, I won’t,” said Alastair, quite flippantly. “We’re already engaged. You can’t possibly be rid of me now. You’re _mine._ ”

The look Thomas gave him was incredibly fond. “Yeah, alright,” he said, kissed Alastair on the forehead again, and handed him back the cup of ice chips. 

* * *

(“Good lord,” Alastair said later that night, having been discharged, taken home, properly dosed and tucked into bed. He was curled up against Thomas’s chest, becoming increasingly appalled while Thomas held out his phone for both of them, playing the footage Cordelia had sent him that morning. “I don’t recall saying any of this. Please don’t let her play this at the wedding.”)

(Cordelia plays it at the wedding.)

**Author's Note:**

> so I could, possibly, be persuaded to write the prequel to this,


End file.
